package daily.kou2022_0308;

import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

//字符串去重
public class Num1 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNext()){
            String str = scanner.next();
            StringBuilder sb = new StringBuilder();
            Set<Character> set = new HashSet<>();
            for (int i = 0; i < str.length(); i++) {
                char c = str.charAt(i);
                //如果不存在，第一次出现
                if (set.add(c)){
                    sb.append(c);
                }
            }
            System.out.println(sb.toString());
        }

    }
}
